Is there built-in a way validate a signature against a specific key?

[Eric Pruitt]

I have multiple public keys in my GPG keyring. When validating
signatures, I sometimes want to validate them against a specific key so
if the file is signed by someone other than the individual or
organization I expect, it will fail. Currently, I do this by creating a
keyring that consists of only one key and using that, and some cursory
searching didn't uncover any alternatives. If there still isn't a GPG
option for validating a signature against a specific key, is there a
particular reason it doesn't exist?

Eric